Universal joint definition
A flexible double-pivoted joint that allows driving power to be carried through two shafts that are at an angle to each other. It consists of two Y-shaped yokes and a cross-shaped member called the spider . The four arms of the spider are assembled into bearings in the ends of the two yokes. With the normal cross-and-two-yoke universal joint there is some change in speed when the driveshaft and the driven shaft are at an angle to each other. The change in speed occurs because the driven yoke and driven shaft speed up and then slow down twice with every revolution of the drive line. The greater the angle between the drive and driven shafts, the greater the speed variation. To eliminate this speed variation, which results in increased wear of the affected parts, constant velocity joints are used on many cars. In front drive vehicles, it is called the constant velocity joint . Also called "Hooke joint" or "cardan joint ."
